Apparatus for adding solids and oxygen to an open hearth furnace



INVENTOR ROBERT W. SM/TH Filed July 27, 1961 TO AN OPEN HEARTH FURNACE R. W. SMITH APPARATUS FOR ADDING SOLIDS AND OXYGEN mhm Lmnw mm 1. NV 5 l J 1 I l 0 H h b m Q mm M mm United States Patent 3,240,481 APPARATUS FOR ADDING SOLIDS AND OXYGEN TO AN OPEN HEARTH FURNACE Robert W. Smith, Pittsburgh, Pa., assiguor to United States Steel Corporation, a corporation of New Jersey Filed July 27, 1961, Ser. No. 127,184 Claims. (Cl. 26634) This invention relates to an apparatus for adding solids and oxygen to an open hearth furnace. The most common way of adding solids to an open hearth furnace is to have the charging machine dump predetermined quantities of material, such as ore and lime, into the furnace during the working period in order to remove excess sulfur, phosphorus, manganese, carbon and silicon. The method of charging takes considerable time and it has therefore been impossible to obtain the maximum production which otherwise would be possible when using oxygen additions to the open hearth furnace. Considerable time is also required for the additions to dissolve into the slag and react with the molten metal. In an attempt to promote faster reaction time the fines have been introduced into the furnace through a lance with the fines being carried in an oxygen or air stream. However, with those previous lances and methods in which the fines are introduced through a single opening, it has been found that there is too much splashing when the oxygen bearing the fines strikes the bath. On the other hand, when the oxygen and fines are introduced through a plurality of small orifices plugging or erosion of the orifices occurs. Also, in order to introduce sutlicient oxygen into the furnace the oxygen must travel at speeds between 450 and 750 ft. per second. This increases the erosion of the orifices and also presents possible damage from a physical explosion due to friction at the high speeds.

It is therefore an object of my invention to provide a lance for introducing gas borne solids together with oxygen into an open hearth furnace.

Another object is to provide such a lance having means for preventing plugging of the outlet due to molten slag and steel splashing into the lance opening during the oxygen blow.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a schematic view of an open hearth furnace equipped with the apparatus of my invention;

FIGURE 2 is an enlarged view, partly in section, of the lance of my invention;

FIGURE 3 is a view taken on the line IIIIII of FIGURE 4; and

FIGURE 4 is a view taken on the line IV--IV of FIGURE 3.

Referring more particularly to the drawings reference numeral 2 indicates a steel producing open hearth furnace having a roof 4 and a hearth 6 containing a bath of molten steel and slag 8. Lance 10 of my invention extends downwardly through a water cooled donut 12 or other opening in the roof and terminates a short distance above the bath. The lance 10 includes concentric tubes 14, 16, 18 and 20 which are connected at their discharge or lower ends by means of a nozzle end 22 welded to the tubes as shown. It will be seen that in addition to the passageway through the inner tube 14 passageways 24, 26 and 28 are provided between the tubes. The nozzle end 22 has an axial opening 30 therethrough of the same internal diameter as tube 14. Six passageways 32 in the nozzle end 22 extend between passageways 24 and 28. Six openings 34 are provided in the nozzle end 22 between passageways 32 in communication with passageway 26. As shown the openings 34 extend inwardly and 3 248,481 Patented Mar. 15, 1966 ICC then diverge downwardly away from the axis of the lance. An opening 36 extends inwardly and downwardly from each opening 34 into the opening 30 preferably adjacent the lower end thereof. The upper part of tube 14 extends through a collar and stulfing box 38 to an elbow 40 which is connected to a tube 42. The collar 38 is fastened to the outer end of tube 16, such as by welding, so as to form a fluid tight connection. A similar collar and stuffing box 44 is fastened to the outer end of tube 18 with the tube 16 passing therethrough and a similar stufling box and collar 46 is fastened to tube 20 with the tube 18 passing therethrough. A water inlet 48 is provided into tube 16 between collars 38 and 44 and an oxygen inlet 50 is provided into tube 18 between collars 44 and 46. A water outlet 52 is provided from tube 20 adjacent the collar 46. One end of flexible supply lines 54, 56, 58 and 60 are connected to one end of conduits 42, 48, 50 and 52, respectively. The other ends of lines 54, 56, 58 and 60 are connected to tubes 62, 64, 66 and 68, respectively. Tube 62 is connected by means of a supply line 70 to a jet liner gun 72 which is supplied with compressed air from line 74. The gun 72 is a standard device manufactured by Engineered Equipment, Inc. of Waterloo, Iowa for mixing air and solids and expelling them under pressure. The jet liner gun 72 travels beneath additive bins 76. A separate bin is provided for each additive such as ore, lime and fluorospar. Tube 64 is connected to a cooling water supply, tube 66 to an oxygen supply, and tube 68 to a water drain. The lance 10 may be raised and lowered by means of a motor which drives a cable drum 82 having one end of a cable 84 attached thereto. The cable 84 passes over a sheave 86 with its other end being attached to the top of lance 10 in any suitable manner, such as by means of a member 88. When the lance 10 is not being used it is raised to the broken line position shown in FIGURE 1 so that it is not subject to the heat of the furnace. When the lance is ready for operation it is lowered through the donut 12 until the lower end is between approximately 4 and 12 in. above the slag in the furnace. In some instances it may be desirable to introduce the solids in an air stream through one lance and the oxygen through one or more lances adjacent the solid lance.

In operation, oxygen alone may be introduced into the furnace 2 through passageway 26 and openings 34. At this time water is also circulated through passageways 24 and 32 to the front end of the lance with the water returning through passageway 28. When the lance is in its lowered position the oxygen stream creates a dish in the bath 8 so as to expose the slag-metal interface. The jet liner gun '72 is moved to a position beneath the bin 76 having ore therein when it is desired to add ore to the bath and beneath the bin having lime therein when it is desired to add crushed lime to the bath. In adding solids, compressed air is delivered to gun 72 through supply line 74 and, depending upon the setting of the gun, between and 1200 pounds of solids per minute are delivered through the opening 30 into the furnace. Thus, the rate of flow of solids can be accurately controlled to deliver the solids into the bath at a maximum rate consistent with the ability of the bath to absorb the added solids. The velocity of the airborne solid stream through nozzle opening 30' is relatively low-between 20 and 200 ft. per second. Oxygen is delivered at the same time through openings 34 at a relatively high velocity-between 450 and 750 ft. per second. The volume of air delivered through opening 30 does not exceed 10% of the amount of oxygen delivered through open ings 34. The discharging oxygen sweeps the solids from underneath the lance, thus dispersing them into the bath. At times metal or slag may enter opening 30 either due (B to splashing caused by the violent reaction of the bath as a result of the oxygen blow or by accidentally submerging of the lance into the bath. This metal or slag is quickly burned away with the oxygen emerging into opening 30 through passages 36. Thus, the lance is always prepared to supply the additives when required.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. A lance comprising a tubular member having a bore with a discharge opening at its forward end, a passageway around said tubular member, and a nozzle end secured to the forward end of said tubular member, said nozzle end having an axial opening therethrough in axial alignment with said discharge opening and an end face surrounding the exit end of said axial opening, said nozzle end having a plurality of openings therein spaced apart.

circumferentially and extending from said passageway to said end face and a plurality of openings spaced apart circumferentially and extending between said passageway and said axial opening.

2. A lance according to claim 1 including means for introducing gas borne solids into said tubular member, and means for introducing oxygen into said passageway.

3. A lance comprising a first tubular member having a bore with a discharge opening at its forward end, a second tubular member having an inner diameter greater than the outer diameter of said first tubular member surrounding said first tubular member and providing a first passageway around said first tubular member, a third tubular member having an inner diameter greater than the outer diameter of said second tubular member surrounding said second member and providing a second passageway around said second tubular member, a fourth tubular member having an inner diameter greater than the outer diameter of said third tubular member surrounding said third tubular member and providing a third passageway around said third tubular member, and a nozzle end secured to the forward ends of said tubular members, said nozzle end having an axial opening therethrough in axial alignment with said discharge opening, an end face surrounding the exit end of said axial opening, a passageway therein extending between said first and third passageways, a plurality of openings therein spaced apart circumferentially and extending from said second passageway to said end face, and a plurality of openings spaced apart circumferentially and extending between said second passageway and said axial opening.

4. A lance according to claim 3 including means for introducing gas borne solids into said first tubular member, means for introducing oxygen into said second passageway, and means for circulating water through said first and third passageways.

5. A lance comprising a first tubular member having a bore with a discharge opening at its forward end, a second tubular member having an inner diameter greater than the outer diameter of said first tubular member surrounding said first tubular member and providing a first passageway around said first tubular member, a third tubular member having an inner diameter greater than the outer diameter of said second tubular member surrounding said second member and providing a second passageway around said second tubular member, a fourth tubular member having an inner diameter greater than the outer diameter of said third tubular member surrounding said third tubular member and providing a third passageway around said third tubular member, and a nozzle end secured to the forward ends of said tubular members, said nozzle end having an axial opening therethrough in axial alignment with said discharge opening, an end face surrounding the exit end of said axial opening, a passageway therein extending between said first and third passageways, a plurality of openings therein spaced apart circumferentially and extending from said second passageway to said end face, said plurality of openings diverging outwardly and forwardly'from the axis of said lance, and a plurality of openings spaced apart circumferentially and extending inwardly and forwardly between said second passageway and said axial opening.

References Cited by the Examiner UNITED STATES PATENTS 2,829,960 4/1958 VOgt 6O 3,010,820 11/1961 Graef et a1. 7551 3,130,252 4/1964 Metz 266-34 X 3,161,499 12/1964 Percy 756O 3,170,016 2/1965 Grace 26634 3,175,817 3/1965 Smith et a1. 266-34 FOREIGN PATENTS 859,293 1/1961 Great Britain.

WHITMORE A. WILTZ, Primary Examiner.

RAY K. WINDHAM, CHARLIE T. MOON, Examiners. 

1. A LANCE COMPRISING A TUBULAR MEMBER HAVING A BORE WITH A DISCHARGE OPENING AT ITS FORWARD END, A PASSAGEWAY AROUND SAID TUBULAR MEMBER, AND A NOZZLE END SECURED TO THE FORWARD END OF SAID TUBULAR MEMBER, SAID NOZZLE END HAVING AN AXIAL OPENING THERETHROUGH IN AXIAL ALIGNMENT WITH SAID DISCHARGE OPENING AND AN END FACE SURROUNDING THE EXIT END OF SID AXIAL OPENING, SAID NOZZLE END HAVING A PLURALITY OF OPENINGS THEREIN SPACED APART CIRCUMFERENTIALLY AND EXTENDING FROM SAID PASSAGEWAY TO SAID END FACE AND PLURALITY OF OPENINGS SPACED APART CIRCUMFERENTIALLY AND EXTENDING BETWEEN SAID PASSAGEWAY AND SAID AXIAL OPENING. 